Letrozole side effects; please help

Hi Flora B sorry I took quite a while to read your message. I have been on the Letrozole now over 2 weeks and the only thing that has changed is that I feel a bit achy in my lower back and that’s one of the side effects but nothing else. Anyway I will see what else may happen as it’s still early days.
Yes it is a very individual thing but it’s nice that you can exchange experiences on here though ?

Do any of you take vitamin D and calcium tabs to combat bone thinning from Letrozole?



I was automatically prescribed Evacal D3 1500mg ( apparently these replaced AdCal ) when prescribed letrozole.  I have some scoliosis in my lower back, and have had back twinges for years - I’m 63 and was diagnosed in March this year - and the bone/DEXA scan showed ‘some’ bone thinning.  I declined the offer of bisphosophonates though, as I won’t risk any ‘jaw necrosis’ as I have pretty rubbish teeth as it is.  ( I think I was extremely fortunate that it was the therapeutic radiography consultant who told me about that, in that it is rare but it does happen  -  I don’t think the oncologist agrees with my self-prescribing, which is fair enough, but I have to live in this body, as much as I appreciate her help and advice ).  I’ve been on Letrozole since June/July.  I can’t honestly say if they are causing me any problems, but my joints are definitely clicking a lot more !! All the best everyone x


Thank you for your concerns. . My surgeon wants to see me again this Friday to discuss  the bone scan.  I am thinking of agreeing to it (once again).

Paulus mentioned self prescribing, and I agree with her that I would not be too happy with any side effect which cripples me. 

Everyone on this forum has their own problems to contend with, yet  they have written kind words of support and advice.  

Best wishes to you all. 

I have just joined Weightwatchers as I have put quite a bit on since my diagnosis due to too much eating, being at home and not working. 


I am a bit confused as I have always used Sucralose in teas, coffees and cereals but since breast cancer was put off as its not a natural product but have just read on the NHS website that its harmless and does not cause cancer.


since my diagnosis I have started using sugar but I want to lose weight so dont like to use sugar and yes I have tried not using any sugar or sweetener but just cant drink coffee or tea without it.


Just wanted to find out what others think or know about this topic



I hae been taking Letrozole for a week, I cant walk or function. My legs gave way whilst out with my dog and I couldnt get up. I just sat there crying till a kind person helped me up. I was so embarrassed. I seem to have most of the side effects listed. I phoned doc and they said try to persevere.

I think I will give it one more week and then just do without it. I dont care if the cancer comes back. I enjoy walking and other outdoor sports and now I cant walk. My poor dog is stressed out because she is used to long walks in the woods. What is not what if. 

Good luck to all the ladies taking this horrible medication

Hi Mss55. 3 days after starting letrozole i literally couldnt walk. It was an absolutly rock bottom point for me. My BCN and 9nc asked me to persevere and after 3 weeks my knee joints were still stiff but the pain had lessened. Walking definitely helped me then! I now have arthritis in both of my shoulders though so 6 months on i am having a months break from letrozole to see if it makes a difference. After 3 weeks my shoulders are no better but i feel like a dark cloud has been lifted off me. I have an apt with my oncology nurse next week to discuss whats next! Hope you find a solution soon and your legs get better xxx

Hello everyone,

I have been on Femara for 3 weeks now and I have a real problem with heat flashes, and especially night sweats. I am 65 years and had moderate symptoms of menopause but now I can heardly manage the night sweats which last a good 30 minutes. I have dozens of heat flashes during the day. They announce themselves with a whiff of nausea. I tried cutting out sugar, and am taking Oxygen mineral supplement. Still thinking of acupuncture or reflexology. Bone pain is not a problem. The eyes may be getting weaker. I had an eye test recently before starting Femara - but there was no problem. Has anyone got similar experiences and share experiences how to get to grips with the temperature fluctuations? I am clothing in layers and constantly keep putting on clothes when shivering after a heat flash, just to take off again soon after that.



Hi everyone

I am 54 and started Letrozole two weeks ago. I am also on Herceptin and Zoladex. I was expecting the hot flushes but so far they have not appeared but the main problem i have is feeling very low and grumpy and a lack of appetite. It feels like a pmt mood but it doesn’t go away. Has anyone else had this problem and if so does it go away afer a time?


I did speak to a nutritionist before i started and she has given me a diet plan to reduce acid reflux and stomache problems. I was doing ok until i had two slices of bread and the wind and tummy pains with indigestion were mad. Not sure if I have an intolerance or it is the Letrozole.


The muscle and joint pains i have with Herceptin seemed to stay constant but i do have some days where my legs seize up. The nutritionist has suggested turmeric capsules which i think are helping. Shoulders, hands and legs are not great and that doesn’t help with the low moods either.


Hoping the side effects ease and the mood lifts over Christmas.     

Thank you Marla and Cybele. I know everyone is different but it is good to know i am not alone in this. Luckily I do have people around me who understand what i have been through and hopefully will bare with me over the coming months/years.



I have mentioned this so many times and had people thanking me! Just take MAGNESIUM!!! It’s amazing. Google it!..I almost stopped taking Letrozole, my whole body ached, I felt like a 90yr old!..it’s a muscle relaxant and gives you energy etc! You will thank me, what have you got to lose? I buy Lamberts (who supply to NHS) take one on a morning and one an hour before I go to bed…and remember MOST of us are deficient in this wonderful supplement! I now get mine on prescription (also take your Calcium D3!)

Please check with your oncologist before taking any additional supplements. You should only take it if you are low on magnesium, and this needs to be established first with a blood test. Any medication that you are already on, needs to be considered.
Sue xx

I was diagnosed with Stage 2 breast cancer in Dec 2016. No one on either maternal or paternal sides have had it, though my mothers side has had many incidents of cancer. I had missed 1 mammogram when my daughter had a bad incident with Crohns disease and we were trying to save her life. Went through chemo, 4 sessions, mastectomy prior, my chouce, no radiation, no lymph node involvement. Due to being a runner for years, skier, and gymnast through high school; I had some joint pain due to injuries. However, nothing prepared me for the after effects of chemo and trying to take Letrozole. Within 2 wks I could barely move, get up from a sitting position or excercise as I wished. I continued to walk 4-5 miles a day, working with a personal trainer etc; until I fell into the back of our car and could not get up. The next day I quit the Letrozole. Within a short time my joints felt so much better. My Oncologist nor his PA were happy. We tried every other day and half doses to no avail. I no longer take it and prefer Quality in my life. I suggest anyone try what is suggested, but I had to stop. My friends who also have gone through this journey tell me how badly they hurt, but some are not as active as I am, or younger. To each their own. Good luck to those sorting this journey out.

That does sound like an extreme reaction and i totally understand why you gave up. I wonder if these professionals would push it so hard if they knew quite how much it messes up our lives.

I have got to week 4 on letrozole and have always been active. I have been told to continue exercise as it helps but it effects me emotionally as well as physically making me cry with the pain. I am thinking i will carry on for now but if it continues at this level after my herceptin finishes in March then i will consider quality of life over the benefits.

Good to know you feel better after coming of it and good luck.

I thought I was tough until I went through Chemo and tried the Letrozole. My friend going through it also having a hard time with the inhibitor. She wants to quit but doesn’t dare, due to having breast and then ovarian. I wish I had seen the forum about trying magnesium. I do not test low, but you know how their normal in testing might not be our normal individually. Found that out when I knew I was dehydrated and I was told my readings were NORMAL. I had to persist until dr ordered the fluids. What a difference. We know our own bodies. Best to you.


I have just been reading this thread as I too am on Letrozole ( have been for about 9 months now ) and have all the usual side effects, stiff joints, depression, head aches etc but they are not too bad I can live with them but a few months ago I had terrible “gastric” problems and I decided to go back to basics and take them as it says on the packet, i.e. with a large glass of water, I also have a large cup of tea and some plain biscuits after taking them and have a large meal before I take them, I make sure the meal I have before them is very starchy/high in carbs, usually lots of boiled potatoes, with just a very small amount of veg and it seems to have stopped the “gastric” problems, I used to eat a lot of veg but it just does not seem to agree with Letrozole so I may end up putting on a bit of weight but if it makes me comfortable for the next five years its a small price to pay.

Any of you that are having gastric problemst may find it worth  trying this kind of change in diet  before you give up taking them all together and I also think drinking plenty of liquids around the time I take them helps.

Good luck.





Fat cells do indeed produce estrogen but that is what your Letrozole is there for to stop them doing that so you dont have to worry about weight its just about getting through all the side effects of the letrozole.



Ditto.  So much negativity.    I felt positive and thankful that there is/are things to help (eg. Radiotherapy, Letrazole) me go forward after my world turned upside down in March 2023, following a routine mammogram.  Im waiting for a date to start 5 sessions of radiotherapy (saw Oncologist last week and just started Letrozole - after wide incision op 7 weeks ago).  But now I’ve read forum posts on both radiotherapy and Letrozole I feel sick with worry again.  So much negativity and so much negativity.  Feel like I’m going into a dark place again and worried.  NHS strikes, no idea when radiotherapy will start (I’m fed up with hearing ’staff shortages in NHS and long waiting lists’.  I was feeling positive but not now.  Worried about side effects, what’s to come and when that might be.  I don’t know what to ask or who to contact tet things moving.  Feel if I don’t try and move things on it will be forever until I hear anything… frustrating but also worrying and scarey. 

Its all scary to be honest, which probably comes over as negative, as we are all flying blind a lot of the time. I was terrified of the radiotherapy, but it was explained to me that radiotherapy is so much more advanced now, and is used with pinpoint precision to the exact area, not the whole breast, so less likely to have any long term side effects. I was also told its like a mopping up of any stray cancer cells, to stop them moving elsewhere in the body, so it seemed a good idea in prevention of a return somewhere else. 

I was very concerned about taking the Letrozole, after reading of some of the side effects. I decided to start and see for myself, as some people have very little to no side effects. I didn’t have any for the first year, and have some now, but they are manageable if you eat healthily and take a few supplements for joints and calcium etc. The surgeon told me any time on letrozole will benefit you in stopping a possible return in the first 5yrs, so just see how it goes! I was more worried about not taking it to be honest, and the cancer returning.

We all have the same fears, and all have to make our own decisions on what to do, when we dont really know what side effects we will get.

Yes, the situation with waiting for radiotherapy is a concern at the moment. I had mine in early lock down, before it got delayed for some.

Not sure how you can hurry it along, as everyone waiting is in the same position regarding delays.

You can contact your breast care nurse with your concerns, who may be able to reassure you at least. I had to wait 4mths after surgery to get my radiotherapy started, so i understand your worry.

@Bluebell22   I agree with @dawn2412. It can be terrifying reading posts in these forums - when I was first directed here after my diagnosis, it scared me so much I didn’t come back to it for over a year!! People who come on these forums are largely a self-selecting group, ie you wouldn’t need to post if everything was tickety boo, so there’s a negative bias from the start. I had WLE in Nov 2021, followed by 5 days of RT in March 22. I think I started the letrozole after the surgery, so I’m c 18 months into it. The RT wasn’t too bad, I was running meetings for work part way through. I was a bit tired for a week or so after, but that was it, and as Dawn says, it’s very targeted to minimise how much they give you, and the radiologists were lovely.

 I’ve always thought of myself as having “breast-cancer-lite”, as others have a much tougher journey than I did, and frankly it’s been a lot easier than the hip replacement I’d had 6 months before the cancer diagnosis, which they’re still working on, but at least my hip wasn’t trying to kill me.

The letrozole has been harder than I expected (but certainly a LOT better than Tamoxifen from what I’ve heard), but most of the time I just get on with life and work around the joint stiffness and random tendons firing off. The low mood could be attributable to many causes in my case, I suffer from mild depression anyway, and life has thrown a whole raft of other nasty challenges at me recently, so it’s hard to pin it down just to these pills, although I doubt that they help. But however decrepit my body feels, I don’t think there’s any way round it and I would far rather be on these than play Russian roulette with the cancer returning.

**The way I viewed my cancer journey was “ok, they’ve found a nasty lump, they’ve cut it out and chucked in the bin, and gave it a kick up the bum with radio therapy, and these pills are my little soldiers to make sure it doesn’t even think about coming back”. Then I just got on with life again. I work in construction and was back up the scaffold 2 weeks after surgery. I have times when the side effects of the letrozole get me down (I won’t lie, sometimes to the point of flattening me), but I do my best to ignore it and just crack on. A trick I **learnt from my horrific arthritis journey was to lose myself in something I enjoy when things get bad. It doesn’t make the discomfort etc go away, but it does push it to the back of your consciousness and gives you a dopamine hit, which does no end of good.

We all have a tendency to fear the worst, but you may be one of those that can cope pretty well with letrozole, (I was blissfully oblivious to all the side effects, even when they were in full flow - I just thought the near robotic stiffness was due to lack of exercise!), and give it a go with an open mind. For me the worst of the side effects were over in the first few months, which was about when I found out it was the pills that made me stiff. I’m glad, in retrospect, that I hadn’t realised it was the pills, or I may have been tempted to stop them, but having got through the worst bit, most of the time I feel fairly “normal” and would rather have this discomfort than cancer any day.